src/basic/terminal-util.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2010 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <sys/ioctl.h>
  21 #include <sys/types.h>
  22 #include <sys/stat.h>
  23 #include <termios.h>
  24 #include <unistd.h>
  25 #include <fcntl.h>
  26 #include <signal.h>
  27 #include <time.h>
  28 #include <assert.h>
  29 #include <poll.h>
  30 #include <linux/vt.h>
  31 #include <linux/tiocl.h>
  32 #include <linux/kd.h>
  33
  34 #include "terminal-util.h"
  35 #include "time-util.h"
  36 #include "process-util.h"
  37 #include "util.h"
  38 #include "fileio.h"
  39 #include "path-util.h"
  40
  41 static volatile unsigned cached_columns = 0;
  42 static volatile unsigned cached_lines = 0;
  43
  44 int chvt(int vt) {
  45         _cleanup_close_ int fd;
  46
  47         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
  48         if (fd < 0)
  49                 return -errno;
  50
  51         if (vt <= 0) {
  52                 int tiocl[2] = {
  53                         TIOCL_GETKMSGREDIRECT,
  54                         0
  55                 };
  56
  57                 if (ioctl(fd, TIOCLINUX, tiocl) < 0)
  58                         return -errno;
  59
  60                 vt = tiocl[0] <= 0 ? 1 : tiocl[0];
  61         }
  62
  63         if (ioctl(fd, VT_ACTIVATE, vt) < 0)
  64                 return -errno;
  65
  66         return 0;
  67 }
  68
  69 int read_one_char(FILE *f, char *ret, usec_t t, bool *need_nl) {
  70         struct termios old_termios, new_termios;
  71         char c, line[LINE_MAX];
  72
  73         assert(f);
  74         assert(ret);
  75
  76         if (tcgetattr(fileno(f), &old_termios) >= 0) {
  77                 new_termios = old_termios;
  78
  79                 new_termios.c_lflag &= ~ICANON;
  80                 new_termios.c_cc[VMIN] = 1;
  81                 new_termios.c_cc[VTIME] = 0;
  82
  83                 if (tcsetattr(fileno(f), TCSADRAIN, &new_termios) >= 0) {
  84                         size_t k;
  85
  86                         if (t != USEC_INFINITY) {
  87                                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0) {
  88                                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
  89                                         return -ETIMEDOUT;
  90                                 }
  91                         }
  92
  93                         k = fread(&c, 1, 1, f);
  94
  95                         tcsetattr(fileno(f), TCSADRAIN, &old_termios);
  96
  97                         if (k <= 0)
  98                                 return -EIO;
  99
 100                         if (need_nl)
 101                                 *need_nl = c != '\n';
 102
 103                         *ret = c;
 104                         return 0;
 105                 }
 106         }
 107
 108         if (t != USEC_INFINITY) {
 109                 if (fd_wait_for_event(fileno(f), POLLIN, t) <= 0)
 110                         return -ETIMEDOUT;
 111         }
 112
 113         errno = 0;
 114         if (!fgets(line, sizeof(line), f))
 115                 return errno ? -errno : -EIO;
 116
 117         truncate_nl(line);
 118
 119         if (strlen(line) != 1)
 120                 return -EBADMSG;
 121
 122         if (need_nl)
 123                 *need_nl = false;
 124
 125         *ret = line[0];
 126         return 0;
 127 }
 128
 129 int ask_char(char *ret, const char *replies, const char *text, ...) {
 130         int r;
 131
 132         assert(ret);
 133         assert(replies);
 134         assert(text);
 135
 136         for (;;) {
 137                 va_list ap;
 138                 char c;
 139                 bool need_nl = true;
 140
 141                 if (on_tty())
 142                         fputs(ANSI_HIGHLIGHT, stdout);
 143
 144                 va_start(ap, text);
 145                 vprintf(text, ap);
 146                 va_end(ap);
 147
 148                 if (on_tty())
 149                         fputs(ANSI_NORMAL, stdout);
 150
 151                 fflush(stdout);
 152
 153                 r = read_one_char(stdin, &c, USEC_INFINITY, &need_nl);
 154                 if (r < 0) {
 155
 156                         if (r == -EBADMSG) {
 157                                 puts("Bad input, please try again.");
 158                                 continue;
 159                         }
 160
 161                         putchar('\n');
 162                         return r;
 163                 }
 164
 165                 if (need_nl)
 166                         putchar('\n');
 167
 168                 if (strchr(replies, c)) {
 169                         *ret = c;
 170                         return 0;
 171                 }
 172
 173                 puts("Read unexpected character, please try again.");
 174         }
 175 }
 176
 177 int ask_string(char **ret, const char *text, ...) {
 178         assert(ret);
 179         assert(text);
 180
 181         for (;;) {
 182                 char line[LINE_MAX];
 183                 va_list ap;
 184
 185                 if (on_tty())
 186                         fputs(ANSI_HIGHLIGHT, stdout);
 187
 188                 va_start(ap, text);
 189                 vprintf(text, ap);
 190                 va_end(ap);
 191
 192                 if (on_tty())
 193                         fputs(ANSI_NORMAL, stdout);
 194
 195                 fflush(stdout);
 196
 197                 errno = 0;
 198                 if (!fgets(line, sizeof(line), stdin))
 199                         return errno ? -errno : -EIO;
 200
 201                 if (!endswith(line, "\n"))
 202                         putchar('\n');
 203                 else {
 204                         char *s;
 205
 206                         if (isempty(line))
 207                                 continue;
 208
 209                         truncate_nl(line);
 210                         s = strdup(line);
 211                         if (!s)
 212                                 return -ENOMEM;
 213
 214                         *ret = s;
 215                         return 0;
 216                 }
 217         }
 218 }
 219
 220 int reset_terminal_fd(int fd, bool switch_to_text) {
 221         struct termios termios;
 222         int r = 0;
 223
 224         /* Set terminal to some sane defaults */
 225
 226         assert(fd >= 0);
 227
 228         /* We leave locked terminal attributes untouched, so that
 229          * Plymouth may set whatever it wants to set, and we don't
 230          * interfere with that. */
 231
 232         /* Disable exclusive mode, just in case */
 233         (void) ioctl(fd, TIOCNXCL);
 234
 235         /* Switch to text mode */
 236         if (switch_to_text)
 237                 (void) ioctl(fd, KDSETMODE, KD_TEXT);
 238
 239         /* Enable console unicode mode */
 240         (void) ioctl(fd, KDSKBMODE, K_UNICODE);
 241
 242         if (tcgetattr(fd, &termios) < 0) {
 243                 r = -errno;
 244                 goto finish;
 245         }
 246
 247         /* We only reset the stuff that matters to the software. How
 248          * hardware is set up we don't touch assuming that somebody
 249          * else will do that for us */
 250
 251         termios.c_iflag &= ~(IGNBRK | BRKINT | ISTRIP | INLCR | IGNCR | IUCLC);
 252         termios.c_iflag |= ICRNL | IMAXBEL | IUTF8;
 253         termios.c_oflag |= ONLCR;
 254         termios.c_cflag |= CREAD;
 255         termios.c_lflag = ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOPRT | ECHOKE;
 256
 257         termios.c_cc[VINTR]    =   03;  /* ^C */
 258         termios.c_cc[VQUIT]    =  034;  /* ^\ */
 259         termios.c_cc[VERASE]   = 0177;
 260         termios.c_cc[VKILL]    =  025;  /* ^X */
 261         termios.c_cc[VEOF]     =   04;  /* ^D */
 262         termios.c_cc[VSTART]   =  021;  /* ^Q */
 263         termios.c_cc[VSTOP]    =  023;  /* ^S */
 264         termios.c_cc[VSUSP]    =  032;  /* ^Z */
 265         termios.c_cc[VLNEXT]   =  026;  /* ^V */
 266         termios.c_cc[VWERASE]  =  027;  /* ^W */
 267         termios.c_cc[VREPRINT] =  022;  /* ^R */
 268         termios.c_cc[VEOL]     =    0;
 269         termios.c_cc[VEOL2]    =    0;
 270
 271         termios.c_cc[VTIME]  = 0;
 272         termios.c_cc[VMIN]   = 1;
 273
 274         if (tcsetattr(fd, TCSANOW, &termios) < 0)
 275                 r = -errno;
 276
 277 finish:
 278         /* Just in case, flush all crap out */
 279         (void) tcflush(fd, TCIOFLUSH);
 280
 281         return r;
 282 }
 283
 284 int reset_terminal(const char *name) {
 285         _cleanup_close_ int fd = -1;
 286
 287         /* We open the terminal with O_NONBLOCK here, to ensure we
 288          * don't block on carrier if this is a terminal with carrier
 289          * configured. */
 290
 291         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 292         if (fd < 0)
 293                 return fd;
 294
 295         return reset_terminal_fd(fd, true);
 296 }
 297
 298 int open_terminal(const char *name, int mode) {
 299         int fd, r;
 300         unsigned c = 0;
 301
 302         /*
 303          * If a TTY is in the process of being closed opening it might
 304          * cause EIO. This is horribly awful, but unlikely to be
 305          * changed in the kernel. Hence we work around this problem by
 306          * retrying a couple of times.
 307          *
 308          * https://bugs.launchpad.net/ubuntu/+source/linux/+bug/554172/comments/245
 309          */
 310
 311         if (mode & O_CREAT)
 312                 return -EINVAL;
 313
 314         for (;;) {
 315                 fd = open(name, mode, 0);
 316                 if (fd >= 0)
 317                         break;
 318
 319                 if (errno != EIO)
 320                         return -errno;
 321
 322                 /* Max 1s in total */
 323                 if (c >= 20)
 324                         return -errno;
 325
 326                 usleep(50 * USEC_PER_MSEC);
 327                 c++;
 328         }
 329
 330         r = isatty(fd);
 331         if (r < 0) {
 332                 safe_close(fd);
 333                 return -errno;
 334         }
 335
 336         if (!r) {
 337                 safe_close(fd);
 338                 return -ENOTTY;
 339         }
 340
 341         return fd;
 342 }
 343
 344 int acquire_terminal(
 345                 const char *name,
 346                 bool fail,
 347                 bool force,
 348                 bool ignore_tiocstty_eperm,
 349                 usec_t timeout) {
 350
 351         int fd = -1, notify = -1, r = 0, wd = -1;
 352         usec_t ts = 0;
 353
 354         assert(name);
 355
 356         /* We use inotify to be notified when the tty is closed. We
 357          * create the watch before checking if we can actually acquire
 358          * it, so that we don't lose any event.
 359          *
 360          * Note: strictly speaking this actually watches for the
 361          * device being closed, it does *not* really watch whether a
 362          * tty loses its controlling process. However, unless some
 363          * rogue process uses TIOCNOTTY on /dev/tty *after* closing
 364          * its tty otherwise this will not become a problem. As long
 365          * as the administrator makes sure not configure any service
 366          * on the same tty as an untrusted user this should not be a
 367          * problem. (Which he probably should not do anyway.) */
 368
 369         if (timeout != USEC_INFINITY)
 370                 ts = now(CLOCK_MONOTONIC);
 371
 372         if (!fail && !force) {
 373                 notify = inotify_init1(IN_CLOEXEC | (timeout != USEC_INFINITY ? IN_NONBLOCK : 0));
 374                 if (notify < 0) {
 375                         r = -errno;
 376                         goto fail;
 377                 }
 378
 379                 wd = inotify_add_watch(notify, name, IN_CLOSE);
 380                 if (wd < 0) {
 381                         r = -errno;
 382                         goto fail;
 383                 }
 384         }
 385
 386         for (;;) {
 387                 struct sigaction sa_old, sa_new = {
 388                         .sa_handler = SIG_IGN,
 389                         .sa_flags = SA_RESTART,
 390                 };
 391
 392                 if (notify >= 0) {
 393                         r = flush_fd(notify);
 394                         if (r < 0)
 395                                 goto fail;
 396                 }
 397
 398                 /* We pass here O_NOCTTY only so that we can check the return
 399                  * value TIOCSCTTY and have a reliable way to figure out if we
 400                  * successfully became the controlling process of the tty */
 401                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 402                 if (fd < 0)
 403                         return fd;
 404
 405                 /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 406                  * if we already own the tty. */
 407                 assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 408
 409                 /* First, try to get the tty */
 410                 if (ioctl(fd, TIOCSCTTY, force) < 0)
 411                         r = -errno;
 412
 413                 assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 414
 415                 /* Sometimes it makes sense to ignore TIOCSCTTY
 416                  * returning EPERM, i.e. when very likely we already
 417                  * are have this controlling terminal. */
 418                 if (r < 0 && r == -EPERM && ignore_tiocstty_eperm)
 419                         r = 0;
 420
 421                 if (r < 0 && (force || fail || r != -EPERM))
 422                         goto fail;
 423
 424                 if (r >= 0)
 425                         break;
 426
 427                 assert(!fail);
 428                 assert(!force);
 429                 assert(notify >= 0);
 430
 431                 for (;;) {
 432                         union inotify_event_buffer buffer;
 433                         struct inotify_event *e;
 434                         ssize_t l;
 435
 436                         if (timeout != USEC_INFINITY) {
 437                                 usec_t n;
 438
 439                                 n = now(CLOCK_MONOTONIC);
 440                                 if (ts + timeout < n) {
 441                                         r = -ETIMEDOUT;
 442                                         goto fail;
 443                                 }
 444
 445                                 r = fd_wait_for_event(fd, POLLIN, ts + timeout - n);
 446                                 if (r < 0)
 447                                         goto fail;
 448
 449                                 if (r == 0) {
 450                                         r = -ETIMEDOUT;
 451                                         goto fail;
 452                                 }
 453                         }
 454
 455                         l = read(notify, &buffer, sizeof(buffer));
 456                         if (l < 0) {
 457                                 if (errno == EINTR || errno == EAGAIN)
 458                                         continue;
 459
 460                                 r = -errno;
 461                                 goto fail;
 462                         }
 463
 464                         FOREACH_INOTIFY_EVENT(e, buffer, l) {
 465                                 if (e->wd != wd || !(e->mask & IN_CLOSE)) {
 466                                         r = -EIO;
 467                                         goto fail;
 468                                 }
 469                         }
 470
 471                         break;
 472                 }
 473
 474                 /* We close the tty fd here since if the old session
 475                  * ended our handle will be dead. It's important that
 476                  * we do this after sleeping, so that we don't enter
 477                  * an endless loop. */
 478                 fd = safe_close(fd);
 479         }
 480
 481         safe_close(notify);
 482
 483         r = reset_terminal_fd(fd, true);
 484         if (r < 0)
 485                 log_warning_errno(r, "Failed to reset terminal: %m");
 486
 487         return fd;
 488
 489 fail:
 490         safe_close(fd);
 491         safe_close(notify);
 492
 493         return r;
 494 }
 495
 496 int release_terminal(void) {
 497         static const struct sigaction sa_new = {
 498                 .sa_handler = SIG_IGN,
 499                 .sa_flags = SA_RESTART,
 500         };
 501
 502         _cleanup_close_ int fd = -1;
 503         struct sigaction sa_old;
 504         int r = 0;
 505
 506         fd = open("/dev/tty", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 507         if (fd < 0)
 508                 return -errno;
 509
 510         /* Temporarily ignore SIGHUP, so that we don't get SIGHUP'ed
 511          * by our own TIOCNOTTY */
 512         assert_se(sigaction(SIGHUP, &sa_new, &sa_old) == 0);
 513
 514         if (ioctl(fd, TIOCNOTTY) < 0)
 515                 r = -errno;
 516
 517         assert_se(sigaction(SIGHUP, &sa_old, NULL) == 0);
 518
 519         return r;
 520 }
 521
 522 int terminal_vhangup_fd(int fd) {
 523         assert(fd >= 0);
 524
 525         if (ioctl(fd, TIOCVHANGUP) < 0)
 526                 return -errno;
 527
 528         return 0;
 529 }
 530
 531 int terminal_vhangup(const char *name) {
 532         _cleanup_close_ int fd;
 533
 534         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 535         if (fd < 0)
 536                 return fd;
 537
 538         return terminal_vhangup_fd(fd);
 539 }
 540
 541 int vt_disallocate(const char *name) {
 542         int fd, r;
 543         unsigned u;
 544
 545         /* Deallocate the VT if possible. If not possible
 546          * (i.e. because it is the active one), at least clear it
 547          * entirely (including the scrollback buffer) */
 548
 549         if (!startswith(name, "/dev/"))
 550                 return -EINVAL;
 551
 552         if (!tty_is_vc(name)) {
 553                 /* So this is not a VT. I guess we cannot deallocate
 554                  * it then. But let's at least clear the screen */
 555
 556                 fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 557                 if (fd < 0)
 558                         return fd;
 559
 560                 loop_write(fd,
 561                            "\033[r"    /* clear scrolling region */
 562                            "\033[H"    /* move home */
 563                            "\033[2J",  /* clear screen */
 564                            10, false);
 565                 safe_close(fd);
 566
 567                 return 0;
 568         }
 569
 570         if (!startswith(name, "/dev/tty"))
 571                 return -EINVAL;
 572
 573         r = safe_atou(name+8, &u);
 574         if (r < 0)
 575                 return r;
 576
 577         if (u <= 0)
 578                 return -EINVAL;
 579
 580         /* Try to deallocate */
 581         fd = open_terminal("/dev/tty0", O_RDWR|O_NOCTTY|O_CLOEXEC|O_NONBLOCK);
 582         if (fd < 0)
 583                 return fd;
 584
 585         r = ioctl(fd, VT_DISALLOCATE, u);
 586         safe_close(fd);
 587
 588         if (r >= 0)
 589                 return 0;
 590
 591         if (errno != EBUSY)
 592                 return -errno;
 593
 594         /* Couldn't deallocate, so let's clear it fully with
 595          * scrollback */
 596         fd = open_terminal(name, O_RDWR|O_NOCTTY|O_CLOEXEC);
 597         if (fd < 0)
 598                 return fd;
 599
 600         loop_write(fd,
 601                    "\033[r"   /* clear scrolling region */
 602                    "\033[H"   /* move home */
 603                    "\033[3J", /* clear screen including scrollback, requires Linux 2.6.40 */
 604                    10, false);
 605         safe_close(fd);
 606
 607         return 0;
 608 }
 609
 610 int make_console_stdio(void) {
 611         int fd, r;
 612
 613         /* Make /dev/console the controlling terminal and stdin/stdout/stderr */
 614
 615         fd = acquire_terminal("/dev/console", false, true, true, USEC_INFINITY);
 616         if (fd < 0)
 617                 return log_error_errno(fd, "Failed to acquire terminal: %m");
 618
 619         r = make_stdio(fd);
 620         if (r < 0)
 621                 return log_error_errno(r, "Failed to duplicate terminal fd: %m");
 622
 623         return 0;
 624 }
 625
 626 int status_vprintf(const char *status, bool ellipse, bool ephemeral, const char *format, va_list ap) {
 627         static const char status_indent[] = "         "; /* "[" STATUS "] " */
 628         _cleanup_free_ char *s = NULL;
 629         _cleanup_close_ int fd = -1;
 630         struct iovec iovec[6] = {};
 631         int n = 0;
 632         static bool prev_ephemeral;
 633
 634         assert(format);
 635
 636         /* This is independent of logging, as status messages are
 637          * optional and go exclusively to the console. */
 638
 639         if (vasprintf(&s, format, ap) < 0)
 640                 return log_oom();
 641
 642         fd = open_terminal("/dev/console", O_WRONLY|O_NOCTTY|O_CLOEXEC);
 643         if (fd < 0)
 644                 return fd;
 645
 646         if (ellipse) {
 647                 char *e;
 648                 size_t emax, sl;
 649                 int c;
 650
 651                 c = fd_columns(fd);
 652                 if (c <= 0)
 653                         c = 80;
 654
 655                 sl = status ? sizeof(status_indent)-1 : 0;
 656
 657                 emax = c - sl - 1;
 658                 if (emax < 3)
 659                         emax = 3;
 660
 661                 e = ellipsize(s, emax, 50);
 662                 if (e) {
 663                         free(s);
 664                         s = e;
 665                 }
 666         }
 667
 668         if (prev_ephemeral)
 669                 IOVEC_SET_STRING(iovec[n++], "\r" ANSI_ERASE_TO_END_OF_LINE);
 670         prev_ephemeral = ephemeral;
 671
 672         if (status) {
 673                 if (!isempty(status)) {
 674                         IOVEC_SET_STRING(iovec[n++], "[");
 675                         IOVEC_SET_STRING(iovec[n++], status);
 676                         IOVEC_SET_STRING(iovec[n++], "] ");
 677                 } else
 678                         IOVEC_SET_STRING(iovec[n++], status_indent);
 679         }
 680
 681         IOVEC_SET_STRING(iovec[n++], s);
 682         if (!ephemeral)
 683                 IOVEC_SET_STRING(iovec[n++], "\n");
 684
 685         if (writev(fd, iovec, n) < 0)
 686                 return -errno;
 687
 688         return 0;
 689 }
 690
 691 int status_printf(const char *status, bool ellipse, bool ephemeral, const char *format, ...) {
 692         va_list ap;
 693         int r;
 694
 695         assert(format);
 696
 697         va_start(ap, format);
 698         r = status_vprintf(status, ellipse, ephemeral, format, ap);
 699         va_end(ap);
 700
 701         return r;
 702 }
 703
 704 bool tty_is_vc(const char *tty) {
 705         assert(tty);
 706
 707         return vtnr_from_tty(tty) >= 0;
 708 }
 709
 710 bool tty_is_console(const char *tty) {
 711         assert(tty);
 712
 713         if (startswith(tty, "/dev/"))
 714                 tty += 5;
 715
 716         return streq(tty, "console");
 717 }
 718
 719 int vtnr_from_tty(const char *tty) {
 720         int i, r;
 721
 722         assert(tty);
 723
 724         if (startswith(tty, "/dev/"))
 725                 tty += 5;
 726
 727         if (!startswith(tty, "tty") )
 728                 return -EINVAL;
 729
 730         if (tty[3] < '0' || tty[3] > '9')
 731                 return -EINVAL;
 732
 733         r = safe_atoi(tty+3, &i);
 734         if (r < 0)
 735                 return r;
 736
 737         if (i < 0 || i > 63)
 738                 return -EINVAL;
 739
 740         return i;
 741 }
 742
 743 char *resolve_dev_console(char **active) {
 744         char *tty;
 745
 746         /* Resolve where /dev/console is pointing to, if /sys is actually ours
 747          * (i.e. not read-only-mounted which is a sign for container setups) */
 748
 749         if (path_is_read_only_fs("/sys") > 0)
 750                 return NULL;
 751
 752         if (read_one_line_file("/sys/class/tty/console/active", active) < 0)
 753                 return NULL;
 754
 755         /* If multiple log outputs are configured the last one is what
 756          * /dev/console points to */
 757         tty = strrchr(*active, ' ');
 758         if (tty)
 759                 tty++;
 760         else
 761                 tty = *active;
 762
 763         if (streq(tty, "tty0")) {
 764                 char *tmp;
 765
 766                 /* Get the active VC (e.g. tty1) */
 767                 if (read_one_line_file("/sys/class/tty/tty0/active", &tmp) >= 0) {
 768                         free(*active);
 769                         tty = *active = tmp;
 770                 }
 771         }
 772
 773         return tty;
 774 }
 775
 776 bool tty_is_vc_resolve(const char *tty) {
 777         _cleanup_free_ char *active = NULL;
 778
 779         assert(tty);
 780
 781         if (startswith(tty, "/dev/"))
 782                 tty += 5;
 783
 784         if (streq(tty, "console")) {
 785                 tty = resolve_dev_console(&active);
 786                 if (!tty)
 787                         return false;
 788         }
 789
 790         return tty_is_vc(tty);
 791 }
 792
 793 const char *default_term_for_tty(const char *tty) {
 794         assert(tty);
 795
 796         return tty_is_vc_resolve(tty) ? "TERM=linux" : "TERM=vt220";
 797 }
 798
 799 int fd_columns(int fd) {
 800         struct winsize ws = {};
 801
 802         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 803                 return -errno;
 804
 805         if (ws.ws_col <= 0)
 806                 return -EIO;
 807
 808         return ws.ws_col;
 809 }
 810
 811 unsigned columns(void) {
 812         const char *e;
 813         int c;
 814
 815         if (_likely_(cached_columns > 0))
 816                 return cached_columns;
 817
 818         c = 0;
 819         e = getenv("COLUMNS");
 820         if (e)
 821                 (void) safe_atoi(e, &c);
 822
 823         if (c <= 0)
 824                 c = fd_columns(STDOUT_FILENO);
 825
 826         if (c <= 0)
 827                 c = 80;
 828
 829         cached_columns = c;
 830         return cached_columns;
 831 }
 832
 833 int fd_lines(int fd) {
 834         struct winsize ws = {};
 835
 836         if (ioctl(fd, TIOCGWINSZ, &ws) < 0)
 837                 return -errno;
 838
 839         if (ws.ws_row <= 0)
 840                 return -EIO;
 841
 842         return ws.ws_row;
 843 }
 844
 845 unsigned lines(void) {
 846         const char *e;
 847         int l;
 848
 849         if (_likely_(cached_lines > 0))
 850                 return cached_lines;
 851
 852         l = 0;
 853         e = getenv("LINES");
 854         if (e)
 855                 (void) safe_atoi(e, &l);
 856
 857         if (l <= 0)
 858                 l = fd_lines(STDOUT_FILENO);
 859
 860         if (l <= 0)
 861                 l = 24;
 862
 863         cached_lines = l;
 864         return cached_lines;
 865 }
 866
 867 /* intended to be used as a SIGWINCH sighandler */
 868 void columns_lines_cache_reset(int signum) {
 869         cached_columns = 0;
 870         cached_lines = 0;
 871 }
 872
 873 bool on_tty(void) {
 874         static int cached_on_tty = -1;
 875
 876         if (_unlikely_(cached_on_tty < 0))
 877                 cached_on_tty = isatty(STDOUT_FILENO) > 0;
 878
 879         return cached_on_tty;
 880 }
 881
 882 int make_stdio(int fd) {
 883         int r, s, t;
 884
 885         assert(fd >= 0);
 886
 887         r = dup2(fd, STDIN_FILENO);
 888         s = dup2(fd, STDOUT_FILENO);
 889         t = dup2(fd, STDERR_FILENO);
 890
 891         if (fd >= 3)
 892                 safe_close(fd);
 893
 894         if (r < 0 || s < 0 || t < 0)
 895                 return -errno;
 896
 897         /* Explicitly unset O_CLOEXEC, since if fd was < 3, then
 898          * dup2() was a NOP and the bit hence possibly set. */
 899         fd_cloexec(STDIN_FILENO, false);
 900         fd_cloexec(STDOUT_FILENO, false);
 901         fd_cloexec(STDERR_FILENO, false);
 902
 903         return 0;
 904 }
 905
 906 int make_null_stdio(void) {
 907         int null_fd;
 908
 909         null_fd = open("/dev/null", O_RDWR|O_NOCTTY);
 910         if (null_fd < 0)
 911                 return -errno;
 912
 913         return make_stdio(null_fd);
 914 }
 915
 916 int getttyname_malloc(int fd, char **ret) {
 917         size_t l = 100;
 918         int r;
 919
 920         assert(fd >= 0);
 921         assert(ret);
 922
 923         for (;;) {
 924                 char path[l];
 925
 926                 r = ttyname_r(fd, path, sizeof(path));
 927                 if (r == 0) {
 928                         const char *p;
 929                         char *c;
 930
 931                         p = startswith(path, "/dev/");
 932                         c = strdup(p ?: path);
 933                         if (!c)
 934                                 return -ENOMEM;
 935
 936                         *ret = c;
 937                         return 0;
 938                 }
 939
 940                 if (r != ERANGE)
 941                         return -r;
 942
 943                 l *= 2;
 944         }
 945
 946         return 0;
 947 }
 948
 949 int getttyname_harder(int fd, char **r) {
 950         int k;
 951         char *s = NULL;
 952
 953         k = getttyname_malloc(fd, &s);
 954         if (k < 0)
 955                 return k;
 956
 957         if (streq(s, "tty")) {
 958                 free(s);
 959                 return get_ctty(0, NULL, r);
 960         }
 961
 962         *r = s;
 963         return 0;
 964 }
 965
 966 int get_ctty_devnr(pid_t pid, dev_t *d) {
 967         int r;
 968         _cleanup_free_ char *line = NULL;
 969         const char *p;
 970         unsigned long ttynr;
 971
 972         assert(pid >= 0);
 973
 974         p = procfs_file_alloca(pid, "stat");
 975         r = read_one_line_file(p, &line);
 976         if (r < 0)
 977                 return r;
 978
 979         p = strrchr(line, ')');
 980         if (!p)
 981                 return -EIO;
 982
 983         p++;
 984
 985         if (sscanf(p, " "
 986                    "%*c "  /* state */
 987                    "%*d "  /* ppid */
 988                    "%*d "  /* pgrp */
 989                    "%*d "  /* session */
 990                    "%lu ", /* ttynr */
 991                    &ttynr) != 1)
 992                 return -EIO;
 993
 994         if (major(ttynr) == 0 && minor(ttynr) == 0)
 995                 return -ENXIO;
 996
 997         if (d)
 998                 *d = (dev_t) ttynr;
 999
1000         return 0;
1001 }
1002
1003 int get_ctty(pid_t pid, dev_t *_devnr, char **r) {
1004         char fn[sizeof("/dev/char/")-1 + 2*DECIMAL_STR_MAX(unsigned) + 1 + 1], *b = NULL;
1005         _cleanup_free_ char *s = NULL;
1006         const char *p;
1007         dev_t devnr;
1008         int k;
1009
1010         assert(r);
1011
1012         k = get_ctty_devnr(pid, &devnr);
1013         if (k < 0)
1014                 return k;
1015
1016         sprintf(fn, "/dev/char/%u:%u", major(devnr), minor(devnr));
1017
1018         k = readlink_malloc(fn, &s);
1019         if (k < 0) {
1020
1021                 if (k != -ENOENT)
1022                         return k;
1023
1024                 /* This is an ugly hack */
1025                 if (major(devnr) == 136) {
1026                         if (asprintf(&b, "pts/%u", minor(devnr)) < 0)
1027                                 return -ENOMEM;
1028                 } else {
1029                         /* Probably something like the ptys which have no
1030                          * symlink in /dev/char. Let's return something
1031                          * vaguely useful. */
1032
1033                         b = strdup(fn + 5);
1034                         if (!b)
1035                                 return -ENOMEM;
1036                 }
1037         } else {
1038                 if (startswith(s, "/dev/"))
1039                         p = s + 5;
1040                 else if (startswith(s, "../"))
1041                         p = s + 3;
1042                 else
1043                         p = s;
1044
1045                 b = strdup(p);
1046                 if (!b)
1047                         return -ENOMEM;
1048         }
1049
1050         *r = b;
1051         if (_devnr)
1052                 *_devnr = devnr;
1053
1054         return 0;
1055 }
1056
1057 int ptsname_namespace(int pty, char **ret) {
1058         int no = -1, r;
1059
1060         /* Like ptsname(), but doesn't assume that the path is
1061          * accessible in the local namespace. */
1062
1063         r = ioctl(pty, TIOCGPTN, &no);
1064         if (r < 0)
1065                 return -errno;
1066
1067         if (no < 0)
1068                 return -EIO;
1069
1070         if (asprintf(ret, "/dev/pts/%i", no) < 0)
1071                 return -ENOMEM;
1072
1073         return 0;
1074 }